SEGA's digital brand manager Ken Balough has confirmed that Sonic the Hedgehog 4: Episode II will not make it to Wii.
In a post on the SEGA forum, Balough confirmed it wouldn't appear on Nintendo's home console:
But no - the reason Episode I was on the Wii was because we wanted to bring the Sonic 4 saga to the widest possible audience. Episode II unfortunately will not be coming to the Wii - for reasons most people have probably guessed, but that doesn't mean the SEGA isn't supporting Nintendo platforms, we have a very strong partnership and will continue to do so.
So there you go.